[bigger stretch]

opinions are like you know what's , everyone has one. That being said here is my opinion. I have had dual corner overflows with durso's , I have had the HOB box type , and I have had the drilled top back with a box , one variant uses two 90 degree pipe fittings instead of a box. My favorite is the drilled back and for these reasons. The drilled area , the holes , are in a low stress area and not under allot of water preasure , takes up far less room in the tank than the usual corner overflow with a hole drilled in the bottom of a tank. The tank can be bought as a regular tank and then taken to one of many aquarium stores to be drilled as the back is rarely tempered , thus allowing you to drain out of the center or the back or drill both sides or both and use one side for a recirculating feed or a feed from your sump. I am sure there are a few other pro's and cons however after having dual corner overflows with durso's in my last 120 I realized that allot of space was wasted , it was hard to aquascape around the over flows , and no matter how much I fiddled with the durso's I could never get them just right , one was , the other never was. ... well there you have it , one mans opinion.